/*
 * Copyright 2002-2014 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package qunar.tc.bistoury.instrument.client.spring.el;

import java.lang.reflect.Constructor;

/**
 * A simple ConstructorExecutor implementation that runs a constructor using reflective
 * invocation.
 *
 * @author Andy Clement
 * @author Juergen Hoeller
 * @since 3.0
 */
class ReflectiveConstructorExecutor implements ConstructorExecutor {

    private final Constructor<?> ctor;

    private final Integer varargsPosition;


    public ReflectiveConstructorExecutor(Constructor<?> ctor) {
        this.ctor = ctor;
        if (ctor.isVarArgs()) {
            Class<?>[] paramTypes = ctor.getParameterTypes();
            this.varargsPosition = paramTypes.length - 1;
        } else {
            this.varargsPosition = null;
        }
    }

    @Override
    public TypedValue execute(EvaluationContext context, Object... arguments) throws AccessException {
        try {
            if (arguments != null) {
                ReflectionHelper.convertArguments(context.getTypeConverter(), arguments, this.ctor, this.varargsPosition);
            }
            if (this.ctor.isVarArgs()) {
                arguments = ReflectionHelper.setupArgumentsForVarargsInvocation(this.ctor.getParameterTypes(), arguments);
            }
            ReflectionUtils.makeAccessible(this.ctor);
            return new TypedValue(this.ctor.newInstance(arguments));
        } catch (Exception ex) {
            throw new AccessException("Problem invoking constructor: " + this.ctor, ex);
        }
    }

    public Constructor<?> getConstructor() {
        return this.ctor;
    }

}
